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Home > 1.ANALOG, ADC > How the voltage reference affects ADC performance, Part 2

How the voltage reference affects ADC performance, Part 2

By Miro Oljaca, Senior Applications Engineer, and Bonnie Baker, Senior Applications Engineer  from Texas Instruments

Introduction

This article is Part 2 of a three-part series that investigates the design and performance of a voltage-reference system for a successive-approximation register (SAR) analog-to- digital converter (ADC). A simplified version of this system is shown in Figure 1. When a design uses an ADC in this system, it is critical to understand the voltage-reference path to the converter. Part 1 (see Reference 1) examined the fundamental operation of an ADC independent of the voltage reference, and then analyzed the performance characteristics that have an impact on the accuracy and repeatability of the system. Part 2 looks at the key charac- teristics of the voltage-reference block in Figure 1 and the reference’s possible impact on the ADC’s performance. Part 2 also shows how to design an appropriate external reference for 8- to 14-bit ADCs. Part 3, which will appear in a future issue of the Analog Applications Journal, will investigate the impact of the voltage-reference buffer and the capacitors that follow it, discuss how to ensure that the amplifier is stable, and provide a reference design that is appropriate for ADCs with 16+ bits.

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Categories: 1.ANALOG, ADC
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